[프로그래머스 Level 4] 저자 별 카테고리 별 매출액 집계하기 (MySQL)

https://school.programmers.co.kr/learn/courses/30/lessons/144856

프로그래머스

 

select author_id, author_name, category, sum(sales * price) as total_sales
from book natural join author natural join book_sales
where date_format(sales_date, '%Y-%m') like '2022-01'
group by author_id, category
order by author_id, category desc